SubqueryWithResult Class Reference

#include <item_subselect.h>

Public Member Functions
	SubqueryWithResult (Query_expression *u, Query_result_interceptor *res, Item_subselect *si)
void	cleanup ()
	Cleanup subquery after complete query execution, free all resources. More...
bool	prepare (THD *thd)
	Prepare the query expression underlying the subquery. More...
void	fix_length_and_dec (Item_cache **row)
bool	exec (THD *thd)
	Execute the subquery. More...
void	print (const THD *thd, String *str, enum_query_type query_type)
bool	change_query_result (THD *thd, Item_subselect *si, Query_result_subquery *result)
	change query result object of subquery. More...
Query_block *	single_query_block () const
enum Item_result	type () const
enum_field_types	field_type () const
bool	may_be_null () const
const Item_subselect *	get_item () const

Private Member Functions
void	set_row (const mem_root_deque< Item * > &item_list, Item_cache **row, bool never_empty)
	Makes storage for the output values for a scalar or row subquery and calculates their data and column types and their nullability. More...

Private Attributes
Query_result_interceptor *	result
Item_subselect *	item
enum Item_result	res_type
enum_field_types	res_field_type
bool	maybe_null
	True if at least one of the columns returned by the subquery may be null, or if a single-row subquery may return zero rows. More...
Query_expression *	unit

Friends
class	subselect_hash_sj_engine

Constructor & Destructor Documentation

SubqueryWithResult()

SubqueryWithResult::SubqueryWithResult	(	Query_expression *	u,
		Query_result_interceptor *	res,
		Item_subselect *	si
	)

Member Function Documentation

change_query_result()

bool SubqueryWithResult::change_query_result	(	THD *	thd,
		Item_subselect *	si,
		Query_result_subquery *	res
	)

change query result object of subquery.

Parameters

thd	thread handle
si	new subselect Item
res	new Query_result object

Return values

false	OK
true	error

cleanup()

void SubqueryWithResult::cleanup

(

)

Cleanup subquery after complete query execution, free all resources.

exec()

bool SubqueryWithResult::exec

(

THD *

thd

)

Execute the subquery.

SYNOPSIS exec()

DESCRIPTION Execute the subquery. The result of execution is subquery value that is captured by previously set up Query_result-based 'sink'.

RETURN false - OK true - Execution error.

field_type()

enum_field_types SubqueryWithResult::field_type ( ) const

inline

fix_length_and_dec()

void SubqueryWithResult::fix_length_and_dec

(

Item_cache **

row

)

get_item()

const Item_subselect * SubqueryWithResult::get_item ( ) const

inline

Returns

the internal Item. Defined only in debug builds, because should be used only for debug asserts.

may_be_null()

bool SubqueryWithResult::may_be_null ( ) const

inline

prepare()

bool SubqueryWithResult::prepare

(

THD *

thd

)

Prepare the query expression underlying the subquery.

This function is called from Item_subselect::fix_fields. If the subquery is transformed with an Item_in_optimizer object, this function may be called twice, hence we need the check on 'is_prepared()' at the start, to avoid redoing the preparation.

Returns

false if success, true if error

print()

void SubqueryWithResult::print	(	const THD *	thd,
		String *	str,
		enum_query_type	query_type
	)

set_row()

void SubqueryWithResult::set_row ( const mem_root_deque< Item * > &  item_list, Item_cache **  row, bool  possibly_empty  )

private

Makes storage for the output values for a scalar or row subquery and calculates their data and column types and their nullability.

Parameters

item_list	list of items in the select list of the subquery
row	cache objects to hold the result row of the subquery
possibly_empty	true if the subquery could return empty result

single_query_block()

Query_block * SubqueryWithResult::single_query_block

(

)

const

type()

enum Item_result SubqueryWithResult::type ( ) const

inline

Friends And Related Function Documentation

subselect_hash_sj_engine

friend class subselect_hash_sj_engine

friend

Member Data Documentation

item

Item_subselect* SubqueryWithResult::item

private

maybe_null

bool SubqueryWithResult::maybe_null

private

True if at least one of the columns returned by the subquery may be null, or if a single-row subquery may return zero rows.

res_field_type

enum_field_types SubqueryWithResult::res_field_type

private

res_type

enum Item_result SubqueryWithResult::res_type

private

result

Query_result_interceptor* SubqueryWithResult::result

private

unit

Query_expression* SubqueryWithResult::unit

private

---

The documentation for this class was generated from the following files:

• sql/item_subselect.h
• sql/item_subselect.cc